1. Field of the Invention
The present invention relates to a recording head cap for sealing an ink discharge orifice of an inkjet recording head, a recording head having the cap mounted thereon, and a method and device for mounting the cap on the recording head. More particularly, the present invention relates to a cap for a recording head that is detachable from a main body of an apparatus.
2. Description of the Related Art
In a recording head that is detachable from an inkjet recording apparatus, as a means (head protecting member) for protecting an orifice-disposed face of the recording head during prolonged storage for transportation or for other purposes, a head-protecting adhesive seal to be bonded to the orifice-disposed face, and a head-protecting elastic cap to be pressed against a row of discharge orifices, are well known. These head protecting members are necessary to protect the orifice-disposed face without causing ink leakage, even when impacts and vibrations are applied from the outside during transportation and storage, or when the environmental temperature varies.
For example, Japanese Patent Laid-Open No. 3-234659 discloses a recording head cap to be mounted on a head cartridge having a combination of an ink reservoir and a recording head, the recording head cap including an engaging section for engaging with the recording head to combine the head cartridge and the cap; a flexible sheet bonded into contact with a discharge orifice of the recording head and an air communicating opening of the ink reservoir; and an elastic member made of sponge or the like and provided at the portion of the flexible sheet corresponding to the discharge orifice.
Furthermore, Japanese Patent Laid-Open No. 4-247954 discloses a recording head cap including an elastically transformable contact member to be in contact with the orifice-disposed face of a recording head, and a pressing means for pressing the contact member against the orifice-disposed face when the cap is mounted on the recording head. The contact member presses the discharge orifice and the neighborhood thereof along the shape of the orifice-disposed face. Examples of materials for the contact member are rubber, thermoplastic elastomer, and the like, which satisfy the requirements of a rubber hardness (JIS A) of 80 degrees or less in order to achieve a satisfactory airtight condition.
The above-described caps are already in practical use as head protecting members for conventional recording heads, and are satisfactory in the present circumstances.
In recent years, however, inkjet recording apparatuses have been required to achieve photographic high-quality and high-definition. For this reason, recording heads also must, for example, have increased orifice density and reduced orifice diameter.
As the results of examination, the present inventors and others have found that the following problems sometimes arise when the conventional head protecting member is used for a recording head that produces high quality and high definition.
That is, since such a recording head has a more complicated structure than the conventional head, the orifice-disposed face thereof is likely to be deformed when a strong force is applied thereto. For this reason:
(1) In the case of a head protecting seal that is adhesive on the side in contact with the orifice-disposed face, there is a risk that the orifice-disposed face will be damaged by the adhesive force of the seal.
(2) In the case of a head protecting cap in which an elastic member of rubber is pressed against the discharge orifices, since the elastic force of such a conventional rubber member causes strong impact resilience, this may deform the orifice-disposed face.
In both the above cases, high-quality and high-definition recording may be impossible.
Although a head protecting cap using a sponge of a urethane foam as an elastic member will not damage the orifice-disposed face of the recording head, the following problems sometimes arise:
Since the pore diameter of the sponge is large (approximately 40 to 70xcexc), the pressing force is apt to be nonuniform. Furthermore, as the storage time becomes prolonged, the sponge undergoes creep deformation, has decreased impact resilience, and is thereby made unable to press the orifice-disposed face with a proper pressing force. At worst, there is a risk that the elastic member cannot cover the orifice-disposed face.
It is accordingly an object of the present invention to address the above problems by making an elastic member in a head protecting cap of a new material that has not previously been used for the elastic member.
It is another object of the present invention to provide a new method of mounting a cap member on a recording head, in connection with the above object or independently, and to more effectively prevent ink from leaking from an orifice-disposed face of the recording head.
In achieve the above objects, according to an aspect of the present invention, there is provided a recording head cap including a solid elastic member for pressing an orifice-disposed face of a recording head, and an engaging section for pressing the solid elastic member against the orifice-disposed face and engaging with the solid elastic member to combine the recording head cap and the recording head, wherein the sponge hardness of the solid elastic member is 10 to 40 degrees, and the repulsive load of the elastic member is damped by 20% or less under compressive elastic deformation of 10 to 60% to be 3 gf/mm2 or more after damping.
According to the above construction, the orifice-disposed face of a high-quality and high-definition recording head, which is structurally apt to deform, is not deformed when pressed by the elastic member. In addition, by using a solid elastic member instead of a porous member such as a sponge, the pressing force against the orifice-disposed face is made uniform, and creep deformation and change in pressing force are restricted during prolonged storage. Therefore, it is possible to provide a head protecting cap capable of protecting the orifice-disposed face of the recording head, which is structurally apt to deform, during prolonged storage. As a specific example of the solid elastic member that satisfies the above features, silicone rubber is given.
Preferably, the solid elastic member is provided with a projection of nearly semicircular cross section that is formed parallel to a row of discharge orifices arranged on the orifice-disposed face of the recording head. This allows the orifice-disposed face to be sealed more reliably. In particular, when the recording head has a plurality of groups of discharge orifices that are able to discharge different liquids, it is preferable that the solid elastic member have projections of nearly semicircular cross section formed parallel to the row direction of the plurality of groups of discharge orifices.
Furthermore, when a flexible film, which is not adhesive to the orifice-disposed face, is provided on the surface of the solid elastic member, the solid elastic member can be made of a material that is difficult to use because of storage stability with respect to ink, thereby widening the choice of materials of the solid elastic member. An area of the solid elastic member in contact with the orifice-disposed face may be coated with a water repellent.
The recording head cap of the present invention is particularly suitable for a high-quality and high-definition recording head, and more particularly, for a recording head in which a surface having energy generating elements for discharging ink opposes the orifice-disposed face.
According to another aspect of the present invention, there is provided a cap mounting method of mounting a cap on a recording head having a discharge orifice for discharging liquid for recording so as to protect an orifice-disposed face of the recording head, including the steps of drawing a flexible film onto the surface of the cap, and mounting the cap with the flexible film drawn thereon onto the recording head so that the flexible film is in contact with the orifice-disposed face.
According to the above-described mounting method, if the surface of the cap in contact with the head is uneven, the flexible film can be easily made to conform to the shape of the cap surface by drawing the flexible film onto the cap. As a result, it is possible to further effectively prevent ink from leaking from the orifice-disposed face of the recording head.
The sponge hardness mentioned in the present invention is obtained by the Asker C hardness measuring method.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.